[1.02] Jeremiah Horrocks, The New Astronomy, And The Transit Of Venus

W. Applebaum (Illinois Institute of Technology)

Horrocks's importance in the history of astronomy has long
been recognized. Working shortly after Kepler's death, he
was among the earliest to adopt Keplerian astronomy, and
went on to improve the Rudolphine Tables. His lunar theory
was the most advanced of his time, its importance
acknowledged by Newton. He is perhaps best known as the
first to predict and observe a transit of Venus, which,
along with other observations led him to improve planetary
parameters and the solar parallax. Although his work was
discovered only a decade after he died, it was deemed
significant enough for Hevelius to publish Horrocks's
treatise on the transit, and for the Royal society to
publish most of his surviving manuscripts.

With the approach of the transit of Venus next June, just
over 120 years after the last one, it is appropriate that we
celebrate Horrocks's achievement in his observation of the
transit of 1639. In the fall of that year Horrocks
discovered, contrary to the best tables of the day
(Kepler's) that the rapidly approaching conjunction would
see Venus on the face of the Sun.

Horrocks notified three others, and prepared himself, using
accounts he had read in Kepler, an account of Gassendiís
observation of the transit of Mercury of 1631, and his own
effort to observe a Mercury transit. Only he and his friend
William Crabtree were able to observe the transit for the
15-20 minutes between its entry on the Sun and sunset.
Horrocks then spent the next year writing several drafts,
all of which were incomplete, when he died in January 1641.

The author(s) of this abstract have provided an email address
for comments about the abstract:
applebaum@iit.edu